The invention pertains to computer pointer control devices. More particularly, the invention pertains to computer pointer control devices adapted for ease of use by handicapped individuals.
The use of pointers on graphical user interfaces (GUIs) presented on a computer display device for interacting with application software is well known. Essentially all Windows(trademark) based or MacIntosh(trademark) based software utilizes such control. Accordingly, apparatus for moving the pointer on a computer screen also are well known to computer operators. Probably the most common pointer control device is a computer mouse such as illustrated in FIG. 1. A computer mouse 10 comprises a shell 12 shaped to fit conveniently and comfortably in the palm of the hand of the user while it rests on a horizontal surface. It typically has two or more buttons 16 and 18 on its top surface positioned to be adjacent the operator""s index and middle fingers when the mouse is gripped comfortably. Protruding from the bottom of the shell is a track ball (not shown) which, responsive to the user moving the mouse on top of the horizontal supporting surface, rotates due to friction with that surface. The track ball is coupled to circuitry (not shown) encased within the shell 12 which determines the direction and amount of rotation of the trackball and converts that to an electrical signal that is provided to the computer via a cable 19 that extends from the back of the mouse and is coupled to a mouse port on the computer. Software within the computer takes that information and converts it into corresponding movements of the pointer on the computer display device.
Although computer mouses of the general form shown in FIG. 1 are probably the most common type of pointer control device, many other types of computer pointer control devices are known. This is particularly true in connection with portable computers (e.g., laptop computers and palmtop computers) since computer mouses tend to be too cumbersome for laptop use. Well known computer pointer control devices other than a mouse include track balls, touch pads, and touch pens. A track ball is very similar to a mouse except that the track ball protrudes upwardly from a surface and the user rotates the track ball by directly placing his or her hand on the track ball and rotating it manually.
Light pens are used in conjunction with touch sensitive screens. A light pen comprises a pen-shaped object which is convenient to hold in the same manner as a pen but having an electrically conductive tip rather than an ink tip. When the light pen touches the electrically sensitive screen, the computer detects the location on the screen where the touch pen contacts the screen.
A touch pad comprises a plurality of layers of material, the top layer simply being a flat surface which can be touched without causing damage. Underneath the top layer are a plurality of rows and columns of electrodes separated by thin layers of insulation to form a grid of electrodes. Beneath the layers of electrodes is a printed circuit board to which the electrodes are coupled. The electrodes receive an alternating current which is interrupted when a conductive object, such as a finger, comes in close proximity to an electrode. In order to operate a touch pad, a user puts his or her finger on the touch pad and moves it about. The electrodes at which interruptions in current occur are detected by the circuit board and and transmitted to the computer. The computer translates that information in order to move a cursor on a computer screen in a manner corresponding to the movement of the user""s finger.
U.S. Pat. No. 5,305,017 discloses one type of touch pad apparatus in common usage. It also contains brief descriptions (with references to more detailed descriptions) of many other types of computer pointer devices, including all of those discussed above and is incorporated herein by reference.
It is noteworthy that all of the most common computer pointer control apparatus require essentially full manual dexterity of the user. To date, little effort has been expended towards creating a computer pointer control device for persons with limited or no manual dexterity.
The invention is a method and apparatus for controlling a pointer on a computer screen adapted for use by individuals with limited or no manual dexterity. A track ball is positioned to protrude from the upper surface of a partially cylindrical base. A mating cradle sits on top of the base with its lower surface in contact with the upper surface of the track ball and the upper surface of the base. The upper surface of the cradle support is shaped to accept the forearm of an operator. The track ball is coupled in a known fashion to circuitry to operate a pointer on a computer screen. The operator can move the cursor up and down on the screen by pushing his or her arm outwardly or inwardly and can move the cursor left to right on the screen by rotating his or her arm in the cradle about its longitudinal axis.
In alternative embodiments, the track ball may be replaced with a touch pad and the bottom surface of the cradle may include a conductive protuberance while the remainder of the bottom surface is non-conductive so as to provide a small contact point between the cradle and the touch pad.